The invention relates to a crown or closure which is preferably used to seal a bottle opening.
Crowns are well known in the art for sealing bottle openings. Such seals are commonly formed of sheet material and comprise a top, a sidewall, and a flared skirt. The skirt includes a plurality of flutes which extend around the circumference thereof at spaced intervals. When applied to cover an open end of a bottle, these flutes bend at the points of intersection between the cap and the skirt, gripping a bead at the upper rim of the opening to seal the bottle.
Typical prior crown designs have incorporated between 21 and 24 flutes, with the current standard crown having 21 flutes. FIG. 1 illustrates a enlarged view of a portion of a standard 21-flute crown design as known in the art. The crown includes a substantially circular top 10 having a downwardly depending skirt 12 and an annular rim or flange 14 extending outwardly from the skirt. The flange 14 is corrugated to provide a plurality of flutes 16. Each flute 16 comprises a substantially trapezoidal-shaped trough or depression 18 defined between a pair of complimentary shaped crests 20.
In this prior design, 21 regions of contact between the trapezoidal depressions 18 and bottle opening are provided when the crown is applied by bending the flange about the bottle opening. To obtain a seal of sufficient strength which will withstand the pressure of carbonated or other beverages typically contained within the bottle, steel is typically used to form the crown. However, the steel is subject to the corrosive effects of the liquid contained within the bottle and also cannot be recycled. Further, the steel edge of the flutes is relatively sharp and can be injurious when grasped by a consumer when the bottle is picked up or opened. This sharp edge can be painful and dangerous when the crown is removed, especially in twist-off bottle designs.